1. Field of the Invention
This invention relates to a method and apparatus for sensing the condition of a gas and, more specifically, to a method and apparatus particularly suitable for analyzing gas in a chamber or conduit where the gas to be analyzed is highly vulnerable to substantial fluctuations in its pressure. As used in this specification the term "condition" or "condition of a gas" is intended to refer to either the physical or chemical or other properties of the gas being analyzed.
2. Description of the Prior Art
Gas analyzers that depend on aspirators or other eductor devices at their exit portion to move the gas sample through the instrument, particularly those using aspirators motivated by air or other gases, suffer from the disadvantage of being very unstable in their operation as the inlet pressure varies. If the motive-fluid pressure is adjusted to obtain the desired sample flow rate with one particular inlet pressure, then higher inlet pressures will cause an excessively high sample flow rate while lower inlet pressures (including vacuums) may result in inadequate sample flow, no flow or reversed flow.
Accordingly, there is a need for a method and apparatus for sensing the condition of a gas or gases in a chamber or flow path when the gas to be analyzed is susceptible to substantial fluctuations in its pressure.